Distillation of tar



DISTILLATION OF TAR Filed Oct. 10, 1928 3 Sheets-Sheet l INVEN 0? afwmi w J 7 ATTORNEYS May 15, 1934. E. H. ELLMS DISTILLATION OF TAR Filed Oct. 10, 1928 3 Sheets-Sheet 2 L? W? I OM M mv A Z w 7 3/ 3 3, M W M u .K 6 4 W y 4,

y 1934- E. H. ELLMS 1,958,849

DISTILLATION 0F TAR Filed Oct. 10. 1928 5 Sheets-Sheet 3 INVENTOR 622 a 5%..

ATTORNEYS Patented May 15, 1934 UNITED STATES.

PATENT OFFICE i DISTILLATION 0F TAR poration of New Jersey Application October 10, 1928, Serial No. 311,459

17 Claims.

This invention relates to improvements in the distillation of tar, and particularly to the utilization of the heat available in the gases produced in coal-carbonization plants to distill tar and to produce pitches and clean oils. The invention will be described especially with reference to its application to coke-ovens.

In the ordinary operation of by-product cokeovens the gases produced by the coking operation pass from the individual ovens through uptake pipes and goose-necks to a collector main common to the ovens of the battery. These foul" gases leave the ovens at high temperature, e. g., 600 to 700 C. or higher, and carry a considerable proportion of volatilized tars and oils as well as solid particles of coke, coal, carbon and other impurities. Ordinarily the gases are rapidly cooled by the application of sprays of ammonia liquor or ammonia liquor and tar in the goosenecks and collector main, the heat in the gases being thereby dissipated and lost. The rapid cooling causes separation of a relatively heavy tar in the collector main. Further cooling is effected in the cross-over main which connects the collector main to the condensing system and an additional quantity of tar carrying both heavier and lighter oils is thus separated. Tarry oil is thrown out of the gases in the condensing system. The various tar fractions are combined and ordinarily shipped from the coke-oven plant to a tar-distillation plant for distillation and separation of the oils and the production of pitches of varying qualities. The cost of handling and of distilling the tar adds materially to the cost of the tar-distillation products.

It is the object of the present invention to provide a method and apparatus which permit the distillation of tar at a coke-oven plant, the utilization of the heat of the coke-oven gases for that purpose, and particularly the production of pitches having various qualities and characteristics and the production of clean oils directly from the coke-oven gases used for such distillation.

In accordance with the present invention the tar to be distilled is subjected to heating by intimate contact with the hot gases from selected ovens of the battery, the tar being introduced thereto in such finely divided condition that the major portion of the tar particles are maintained in suspension in the hot gases which are at a temperature at which the desired portion of the oils will be vaporized from the tar and retained in the gases in the vapor phase. The gases are subjected then and while still at a sufliciently high temperature prevent condensation of the oils, to cleaning, e. g., to electrical precipitation to separate solid and liquid particles from the gases, leaving only the clean oil vapors. The gases may be cooled thereafter to condense the 60 vapors and to recover thus the clean oils as products of the operation.

The heat available in the gases from a cokeoven battery is many times the amount required to distill all of the tar produced by that battery. Consequently only a portion of the available gases need be utilized in accordance with the present invention if only the tar from the battery is to be distilled. Tar from other sources, such as horizontal retort tar, vertical-retort tar, watergas tar, etc., may also be distilled in the manner hereinafter described and the gases from any number of ovens can be utilized for such distillation. The amount of the gases thus utilized will depend, therefore, upon the available supply of tar to be distilled. The distillation operation may be conducted continuously or intermittently as desired. If only a limited quantity of tar is available it may be accumulated and distilled as hereinafter described and the distillation may 50 then be discontinued until a further quantity of tar has been accumulated, or the tar may be distilled as produced by utilizing the gases from only a few of the ovens.

The distillation of the tar is effected readily by introducing it to the stream of hot gases in extremely finely divided condition, for example, by spraying the tar into the stream of gases through suitable spray nozzles provided for that purpose. These spray nozzles should be of such a character as to insure extremely fine sub-division of the tar particles so that they will be carried by the stream of gases, the velocity of which is adjusted to avoid so far as possible the precipitation of tar particles. High pressure nozzles using pressures of 200 to 4000 pounds per square inch and very small orifices may be used. Instead of spray nozzles, other means for atomizing or nebulizing the tar may be employed. The intimate contact of the tar particles with the hot gases results in the distillation and separation therefrom of oil vapors, leaving smaller particles of tarry or pitch constituents still suspended in the gas stream.

The dew points of the gases for the several constituents carried therein as vapor are lower than the normal boiling points of these constituents and by suitable regulation of the temperature of the gases during the distillation and especially during the subsequent treatment of the 9 gases as hereinafter described, it is possible to retain the desired oils as vapors while the tarry constituents remain in the liquid phase. The temperature of the gases should, to accomplish the intended purpose, be maintained above the dew point of the gases for the most readily condensable of the desired oil,constituents so that substantially all of the desired oils will remain in the vapor phase and will be carried over with the gases after the separation of the tarry constituents therefrom. The tarry constituents in the form of globules of pitch and tar fog tend to remain suspended in the gas stream but are readily separated therefrom in an electrical precipitator or other cleaning means.

By adjusting the various factors affecting the distillation such as the temperature and velocity of the gases and the character and amount of tar supplied, the amount of distillation may be varied to change the character of the pitch constituents which remain in the gas stream. By separating such pitch constituents under regulated temperature conditions in a device adaptcd to remove such entrained particles from a hot gas, the character of the pitch recovered may be varied and products may be obtained which can be utilized directly in the trade. Similarly, the nature and character of the oil vapors passing from the gas cleaning device can be varied and by total or fractional condensation of such vapors oils suitable for commercial uses can be obtained.

Instead of spraying the tar to be distilled into the gases by means of spray nozzles. the tar may be agitated in a suitable receptacle through which the hot coke-oven gases are passing at the requisite velocity, the agitation being designed to throw the tar into the gas stream in the form of extremely finely divided particles. Such an agitator may comprise a cylinder adapted to be retated at high speed, i. e., 600 to 1500 or more revolutions per minute. Such a cylinder may be from ten to eighteen inches in diameter, have either a smooth surface or be composed of discs of alternate different diameters and be arranged to dip slightly into or just touch the body of tar in the receptacle, for example, to a depth of onesixty-fourth of an inch or less. The rapid rotation of the cylinder throws the tar into the gas stream in a finely divided spray comparable with that produced by the spray nozzles.

The depth to which such a cylinder dips into the tar determines the character of the spray which is formed. According to this invention the operation of the cylinder is so adjusted that the tar is thrown from the cylinder in such finely divided condition that the major portion of it does not settle out of the gas but is carried forward by the gas until removed therefrom in the cleaning operation. A suitable time interval is allowed between the spraying of the tar into the gases and the cleaning of the gases so that distillation of the tar by the hot gases will take place (-0 the desired degree before the entrained tar or pitch resulting from the distillation is removed from the gases.

A sufficiently fine spray of tar may be obtained by causing a jet of tar to flow against a suitable rotating surface over which a stream of gas. such as steam or a fuel gas. is moving. For example, tar may be caused to flow onto a rotating cone or disc, across the edges of which a high velocity flow of coke-oven gas is maintained.

Other means for producing a sufficiently fine tar spray may be employed. A spray suited to the practice of this invention must be extremely fine. In such a spray the ratio of the surface of liquid in contact with the hot gases to the weight of the liquid employed is extremely high. This tends toward highly efficient distillation. The extent to which the distillation is carried is dependent not only upon the fineness of the spray and the length of time during which the tar is in contact with the hot gases, but also the temperature of the gases. The gases may advantageously be employed at or near their maximum temperature.

The gases employed for distillation according to this invention may be collected from selected ovens of a coke-oven battery, or selected units of other coal carbonization apparatus in a header and used directly for distillation without any preliminary treatment. Optionally a portion of the gases from the usual collector main may be employed for the distillation or a short collector main provided with ammonia liquor or tar sprays or other means for preventing the accumulation and coking of pitch may be employed for collecting the gases from selected units. Tar or ammonia liquor or both may be sprayed into such a short collector main in regulated amount in order to cool the gases to some predetermined temperature before using them for distillation. The amount of cooling effected in this short collector main will generally be slight. so that the exit gases will be at or near the maximum temperature attainable at this point. The short collector main used for collecting the gases to be employed for distillation may be a portion of the usual main blanked off from the usual main for this purpose, or a short main distinct from the usual main may be employed. The short main may advantageously be situated at the rear of the battery of ovens, and connected through uptake pipes of the usual type with selected ovens. By the proper adjustment of valves in these uptake pipes and valves in the usual uptake pipes connecting these selected ovens with the ordinary collector main. the gases from the selected ovens may be passed into the ordinary collector main or passed to the short collector main at will.

The apparatus for atomizing or nebulizing the tar into the hot gases will advantageously be situated close to the short collector main or other means employed for collecting the hot gases from the various coal distillation units so that the loss of heat from the gases by radiation will be kept at a minimum. The various parts of the apparatus may advantageously be insulated to prevent loss of heat by radiation.

Beyond the atomizing or nebulizing apparatus is a distilling chamber or contact chamber which may advantageously be a part of the cross-over main of the battery or another main of similar diameter. The velocity of the gases in this contact chamber must be such as to maintain the suspension of the tar spray in the gases. This is best accomplished by using a contact chamber of small cross-sectional area.

From the distillation or contact chamber the gases pass through suitable cleaning means in which the spray of tar or pitch resulting from the distillation is removed from the gases while the gases are at sufiiciently high temperature to retain the vapors f om the distillation. as such. The gasses may be cleaned in a gas scrubber of the type usually employed for removing "tar fog etc. from coal carbonization gases. or an electrical precipitator may be employed.

Substantially all of the 'tar and pitch constituents can be separated from thegases in an electrical precipitator such, for instance, as the well known Cottrell precipitator operated at substantially the temperature required to maintain the desired oil constituents in the vapor phase, that is to say, at a temperature higher than the dew point of the gas for the most readily condensable of the desired oil constituents therein. -The gases freed .of tarry constituents will upon cooling yield clean oils substantially free from contaminaton. by tar and pitch;

The gases which are thus cleaned will upon total condensation yield a mixture of oilcon stituents. The dew points of the gases for these several constituents are diiferent and it is possible by fractional condensation to recover oils having varying characteristics. These oils, being substantially free from tarry constituents and other impurities, are in condition for immediate utilization for the purposes to which oils commonly obtained by distillation of tar are adapted.

The gases carrying the vapors produced by distillation and-the particles of tar or pitch are'delivered.at the requisite temperature to the electrical precipitator which is disposed preferably as close as possible to .the atomizing device and yet at suflicient distance therefrom to permit the desired distillation of the tar to take place. This arrangement is desirable in order that the temperature of the gases may not be reduced unduly before electrical precipitation of the pitch constituents is accomplished. The electricalprecipitator should be constructed so as to withstand the high temperatures to which it is subjected. It may be insulated advantageously to avoid loss of heat from the gases. This is particularly desirable if the recovery of the maximum quantity of heavy oils from the gases subsequent to cleaning is I desired. a

The operation of an electrical precipitator consists in passing the gas to be treated between electrodes whose difference in electrical potential is very great. Experience has shown that it is best to use a rectified alternating current. The alternating current (the primary) issent through a step-up transformer to produce a high potential current (the secondary) which is then rectified to an intermittent uni-directional current, for example, by means of a rotary converter. The rectified current is delivered from the converter to the electrical precipitator at practically the potential at which it leaves the transformer.

The electrical precipitator consists essentially of a group of vertical pipes with a wire or rod in the center of each. the pipes being connected to proper headers for introduction and discharge of the gases. The pipes generally constitute the positive electrodes and the wires or rods the negative electrodes. The size of the pipes as commonly used varies, but in general pipes of less than six inches in diameter are not employed. Electrical precipitators with tubes six inches in diameter using secondary voltages from 35,000 to 50,000 volts are satisfactory for the purposes of this invention. It is generally best to operate with maximum potential difference (secondary' current) between electrodes, this maximum being just below the break-down voltage at which arcing occurs.

The efliciency of the clean ng is dependent upon several variables. Satisfactory cleaning of the gas may be accomplished if the time of treatment is of the order of one second although this and one-half to two seconds, that is, with a gas velocity of from 6 to 4.5 feet per second. This gives an emciency of cleaning of approximately ninety-nineper cent. If the time of treatment is shorter, for example, a treatment of from 0.5 to one second, that is, with a gas velocity of from 18 feet to 9 feet per second, small amounts of tar or pitch may pass over with the gases to the oil condensers.

From the electrical precipitator the gases carrying the condensable vapors may be conducted through suitable condensing apparatus including coolers, scrubbers, fractional condensers, fractionating columns, etc., designed to reduce the temperature of the gases and to cause the separation of oils therefrom.v One total oil fraction may be collected if the gases are cooled in one step to the lowest desired temperature. Several oil fractions may be recovered if the gases are cooled by stages in coolers designed for separate collection of oils corresponding to the individual cooling steps.

Electrical precipitators of the type employed for initial cleaning of the' gases may be used to separate the" condensed vapors. By passing the gases through such precipitators at predetermined temperatures the condensed constituents can be separated effectively and sharp cuts of oil can be obtained. The gases, afterthe suc-' cessive condensations accompanied by separation of the oil constituents can be conducted through the usual equipment provided for the purpose of cooling the gases and recovering the other valuable constituents such as ammonia and lights oils therefrom.

The invention as described does not interfere with the normal operation of a coke-oven battery or require modification of the usual apparatus employed in connection with by-product cokeovens. The ovens of the battery are conriected in the usual manner too. common collector main in which the gases are cooled with ammonia liquor or ammonia liquor and tar. The partially cooled gases are delivered through a crossover main to the condensers and the tar and tarry oil which separate from the gases may be recovered in the usual way ahd can be subjected to distillation as hereinbefore described by intimate contact with the hot gases from selected ovens. The special distillation equipment can be used when required and when the distillation equipment is not in operation the gases from the ovens which are connected thereto can be directed into the usual collector main and treated with the gases from the other ovens of the battery.

The invention is of more or less general application to the distillation of tar and oils and to the recovery of clean oils therefrom. It will be further illustrated by the following more detailed description taken with the accompanying drawings which show apparatus embodying the invention and adapted for the practice of the process, but it is intended and will be understood that the invention is not limited to the speciflc details of the apparatus as illustrated in the drawings, in which v Fig. 1 is a plari view of a portion of a cokeoven battery illustrating the application of the invention by the use of a spray nozzle} Fig. 2 is an enlarged sectional view of the spray nozzle, contact chamber and electrical precipitator;

Fig. 3 is a section through the electrical precipitator at right angles to the section shown in Fig. 2;

Fig. 4 is a plan of a portion of a coke-oven battery illustrating the employment of a rotating cylinder in applying this invention;

Fig. 5 is an enlarged vertical section of the atomizing chamber shown in Fig. 4;

Fig. 6 is a section of the atomizing chamber taken on line 66 of Fig. 5;

Fig. 7 is a section on the line 7-7 of Fig. 5;

Fig. 8 is a plan view of a portion of a cokeoven battery illustrating another means for atomizing the tar into the hot-coke-oven gases; and

Fig. 9 is a section on the line 99 of Fig. 8.

Referring to the drawings, 5 indicates the battery of coke-ovens in which the individual ovens are connected by uptake pipes and goose-necks 6 to a collector main '7 having a center boX 8 from which a cross-over main 9 conveys the gases and vapors to the condensers 10 and 11. Cooling is effected in the collector main and the goose-necks leading thereto by a suitable cooling medium such as ammonia liquor or ammonia liquor and tar which is introduced through spray nozzles 12 which may be connected by a pipe 13 to any suitable source of the cooling agent. Tar and ammonia liquor may be drawn off from the center box 8 to the decanter 14. Further cooling is effected in the condensers and the tar and oil which separate from the gases are withdrawn therefrom to a decanter 15 wherein the ammonia liquor is separated from the tar and oils. The ammonia liquor may be delivered to a receptacle 15 from which it may be withdrawn as required for use as a cooling medium or for the purpose of recovering ammonia therefrom. The separated tar may be delivered to a receptacle 16 for storage until required for distillation. A separate receptacle 17 may be provided for the storage of other tar. From the condensers 10 and 11 the gases may be delivered to an exhauster 18 which maintains the pressure balance in the system. They may be conveyed thence through the usual equipment for the separation of light oils, etc., therefrom. The apparatus as described is that usually provided in by-product recovery systems and other similar equipment may be used in place thereof.

In carrying out the present invention, a number of selected ovens of the battery may be connected through uptake pipes and goose-necks 19, preferably at the rear of the ovens, with a short collector main or header 20. Although in the drawings no spray means is shown in this short collector main 20, means for spraying and cooling the gases may be supplied when it is desired to cool the gases at least to some extent before spraying the tar to be distilled into them. Tar or ammonia liquor, or a mixture of both, may be employed for cooling these gases. Where desirable, suitable spray means may be provided in this short collector main merely for flushing the main to prevent accumulation of pitch therein with subsequent coking of the pitch to coke. Where spray means is provided in this short collector main, a draw-off should be provided and the material drawn off from the short collector main may advantageously be run into a decanter and the tar subsequently sprayed into the hot gases through the spray nozzles or other atomizing or nebulizing means hereafter to be described.

The hot gases from the selected ovens pass through the header or short collector main, past means for atomizing tar into the gases, into the distilling or contact chamber where the tar carried in suspension in the gases is distilled.-

In Figs. 1 and 2 a high pressure spray nozzle 21 is provided in the atomizing chamber 22 for finely atomizing or spraying the gases with finely divided tar. The atomizing chamber is shown as a cylindrical chamber connected to the short collector main and separated from the distilling chamber or contact chamber 23 by the conical section 24. The atomizingchamber contains the spray nozzle 21 which supports the bafile plate 25. This baffle plate is circular and so situated that it causes the gases to pass evenly through the opening in the conical section 24, The conical section extends into the contacting chamber a short distance in order that the spray from the nozzle may not impinge immediately upon the walls of the contact chamber. The tar to be distilled is supplied to the nozzle from any suitable source such as the tanks 16 and 17. by means of the pumps 26 and 27 and high pressure pump 28. A by-pass 29 and pressure gauge 30 are provided for regulating the pressure in the nozzle. The small amount of tar which impinges upon the conical section or is otherwise caused to collect in the bottom of the atomizing chamber may be drawn off and recirculated through the nozzle. The atomizing chamber is provided with cleanout plates 31. Any tar contacting with the walls of the distilling chamber is drained by gravity into the bottom of the precipitator 32. The size of the contact chamber 23 should be such as to insure sufiicient velocity to the gas to maintain the major portion of the tar particles in the gasstream during the passage thereof through this chamber. A velocity of 20-40 feet per second is suitable but may be varied with varying weights of spray particles.

The precipitator 32 is disposed at the end of the contact chamber so as to receive the gases at maximum temperature therefrom. It may consist of a number of tubes 33 supported in heads 34 and 35. An inlet 36 near the bottom of the preeipitator communicates with a chamber 37 which is partially separated from the tube section by a baffle 38. An outlet 39 permits the escape of gases from the separator after the latter have passed through the tubes.

A plurality of electrodes 40 preferably in the form of metal rods extend through the tubes and are supported from a bus-bar 41 located near the upper end of the tubes. The bus-bar 41 at the top of the separator extends at both ends into casings 42 which enclose insulators 43 upon which the bus-bar is supported. The high tension current lines extend into the casings 42 and connect with the bus-bar 41, thus supplying the necessary current from any suitable source of uni-directional current under high tension. The casing of the separator 32 is grounded or otherwise connected to the source of current to complete the circuit. The casing and tubes form the positive electrode, the electrodes connected to the bus-bars being negative. The form and arrangements of the conductors in the circuit may be varied. The arrangement should be such as to supply high tension uni-directional current to the electrodes. thereby permitting a continuous silent discharge between the electrodes and the tubes through which the gases pass.

The gases carrying tar or pitch in suspension in the form of fine globules, together with solid materials from the coke-ovens such as carbon, etc., in finely divided form, enter the electrical precipitator from the contact chamber and pass through the tubes in the precipitator, b ing subjected therein to the electrical discharge which through ionization of the solid and liquid particles causes them to separate from the gases and condensable vapors. The separated liquids, together with the solid particles, run down the inner walls of the tubes into the chamber 3'7 from which the pitch is withdrawn through a pipe 44 from the bottom of the-precipitator.

The gases carrying the condensable vapors escape through a pipe 45 to condensers 46 which may be fractional condensers designed to reduce the temperature of the gases in stages and to separate the oil in fractions from the gases. The separated oil can be delivered through pipes 47 to receptacles 48. After separation of the oils the gases can be conveyed through a cross-over main 49 to the exhauster and mingled with the gases from the remaining ovens of the battery. The tar or pitch withdrawn from the separator through the pipe 44 may be delivered to a pitch receptacle 51.- The pitch may be withdrawn through a pipe 52 for any desired use.

The arrangement for distilling tar and hot coke-oven gases shown in Figs. 4 and 8 is similar to that shown in Figs. 1 and 2 except that in each of the Figures 4 and 8 a different arrangement isshown for atomizing the tar into the hot gases.

In Fig. 4 the short collector main or header 20 is shown connected through the atomizing chamber 60 with the contact chamber 23. Beyond the her is supplied with clean-out plates 62. Cleanout plates are also provided atthe ends of the main 20. Hot gases from the ovens pass through the header 20; through the ante-chamber and through the atomizing chamber 60, into the contact chamber 23 in which distillation of the fine tar spray into the hot gases takes place. As the gases pass through the chamber 60, they pick up and carry with them the very finely divided spray of tar produced by the rotating cylinder 63. The bottom'of the atomizing chamber contains a small body of tar supplied by the pipe 64 and maintained at constant level by the overflow 65. The cylinder 63, which may be about ten inches in diameter, is so situated that it dips into this body of tar to a-very slight extent, say, for exampleJ/ar of an inch or less. The cylinder 63' is driven by the motor 66, through the shaft 67 at a speed of, for example, 600 to 1500 R.'P. M. producing an extremely fine spray of tar. As the cylinder rotates, this spray of tar leaves the surface of the cylinder'at various points and each' particle leaves in a path which is tangential to the cylinder, at the point of departure of the The gas is travelling at such a velocity that it carries the particles of tar on through the contact chamber in suspension in the gases, into the electrical precipitator. Most of the tar leaves the cylinder before projection along a path which would cause impingement of the tar on the baffle 69. The principal function of the batlie 69 is to direct the flow of gas and to protect the cylinder and tar in the! bottom of the chamber 60 from contact with the gas.

Substantially all of the spray which passes between the battles will be so fine that it will be carried by the gases in suspension as far as the precipitator. The proportion of tar thrown from the cylinder, which passes between the baiiies, may be varied by adjusting the position of the baflie 68.

Li operating the apparatus shown in Fig. 4, the gases from the selected ovens pass through the atomizing chamber 60 in which tar fed into the bottom of the chamber through the feed line 64 is atomized into the gas by means of the cylinder 63. The tar overflow 65 regulates the depth of tar in the atomizing chamber and the tar is fed to the chamber at such a rate that there is a continuous overflow over the weir 65 into the collector cup 70. This overflow is conveyed by the line '11, back to the source of tar supply or may be directly recirculated through the atomizing chamber. The feed may be so adjusted that the overflow will be very small. This overflow will consist of substantially unchanged tar.

According to the arrangement shown in Fig. 8,

tar, which is fed to the atomizing chamber through the feedline 81, is caused to flow upon the rapidly rotating cone 82. The cone 82 is mounted upon the shaft 83, which is driven at the desired rate of speed by the motor 84. The atomizing, chamber 80, through which the shaft 83 passes, is a cylindrical section with conical sections at either end. The conical section at the forward end of the chamber 80, i. e., at the the short collector main or header 20 shown in Fig. 1.

Within the chamber 80 is a fan 90 mounted on the shaft 83, which also bears the cone 82. The tar is fed through the pipe 81 onto the rotating cone and is thus atomized into the gases. A narrow annular space is left between the baffle 85 and the cone 82 for the passage of the hot gases. The fan draws hot gases through the passage 91 from the oven served by the uptake and goose-neck 87, and, where necessary, from the main 89 also. The gases from the five ovens indicated in the drawings are all passed into intercommunicating passages. The gases from the oven 87 may all be passed through the passage 91 or they may in part pass through the passage 88 and the passage 92 directly into the distilling chamber 23. ing through the passage 91 may comprise gases passing through the uptake 87 and gases from other ovens which are conducted through the passage 88 to the passage 91. The fan forces On the other hand, the gases passthe gas passing through the passage 91 through the narrow annular space between the cone 82 and the baiile 85, and thereby finely atomizes the tar which is made to contact with the rapidly rotating cone, and the fine tar particles thrown off from the end of cone 82 are entrained by the rapidly moving gases. The annular space between the cone and the bailie 82 is of such size as to give a high gas velocity, and the fan is driven at such speed as to maintain suitable suction on the passage 91 to maintain the gas speed desirable.

That part of the atomizing chamber indicated by the numeral 86 is separated from the contact chamber 23 by the baffles 93. Hot gases from the ovens pass through the passage 92 between the bafiles 93 into the contact chamber 23, and the finely atomized tar is here mingled with these hot gases and distillation of the tar is effected. The gases, with the tar particles entrained therein, pass along through the contact chamber or distilling chamber 23 to the cleaning apparatus indicated by the electrical precipitator 32. The apparatus is so constructed that tar, which col lects in the bottom of the chambers and 86 may be recirculated and again sprayed onto the cone 82 from the pipe 81.

The contact chamber 23 drains by gravity into the precipitator 32. Tar or pitch which contacts with the walls of the apparatus, is thus blended in the precipitator with the pitch removed from the gases. Separate means for recovering tar from the contact chamber and the precipitator may be provided in this type of appa ratus or the other types of apparatus shown herein.

Modifications of the apparatus disclosed above may be made to suit various conditions. The invention may be applied to gas retort plants, water gas plants, gas producers, low temperature carbonization retorts, etc., by adapting the apparatus herein disclosed to these various types of coal carbonization plants. The invention relates primarily to the distillation of tar by the employment of the hot gases from a coal carbonization plant. The tar to be distilled is atomized into such fine droplets that the droplets are carried in suspension by the gases for a sufficient length of time to allow the desired distillation of the tar by the hot gases. The tar or pitch resulting from the distillation, and other particles entrained in the gases, are removed by suitable cleaning means, while the gases are still at a high temperature and contain valuable ingredients in the vapor state. The gases and vapors, after cleaning, are cooled to recover clean oils. The conditions of operation may be so adjusted that pitches having desired characteristics and valuable clean oils are recovered as products of the operation. It will be understood that the description is illustrative and that various changes may be made in the form and arrangement of the apparatus employed in the steps utilized herein without departing from the invention or sacrificing any of the advantages thereof.

I claim:

1. The method of distilling tar, which comprises suspending and carrying finely divided particles of the tar to be distilled in a stream of hot coal-carbonization gases at a temperature at which the oil constituents of the tar are vaporized and retained in the vapor phase, removing entrained solid and liquid particles from the gases and cooling the gases to condense the vapors.

2. In the distillation of tar the step which com prises spraying and carrying finely divided particles of the tar to be distilled in a stream of hot coal-carbonization gases at a temperature at which the oil constituents of the tar are vaporized and retainedin the vapor phase and subjecting the gases and vapors to electrical precipitation to remove solid and liquid particles from the gases.

3. In the distillation of tar the step which comprises suspending finely divided particles of tar to be distilled in a stream of hot coal-carbonization gases travelling at a velocity sufficient to retain substantially all the particles in suspension and at a temperature at which volatile oil constituents of the tar are vaporized from the tar particles while in suspension and retained in the vapor phase and subjecting the gases and vapors to electrical precipitation to remove solid andliquid particles from the gases.

4. The method of distilling tar, which comprises suspending finely divided particles of tar to be distilled in a stream of hot coal-carbonization gases travelling at a velocity sufiicient to retain substantially all the particles in suspension and at a temperature at which volatile oil constituents of the tar are vaporized from the tar particles while in suspension and retained in the vapor phase, subjecting the gases and vapors to electrical precipitation to remove solid and liquid particles from the gases and cooling the gases to condense the vapors.

5. In the distillation of tar the step which comprises spraying finely divided particles of tar to be distilled in a stream of hot coal-carbonization gases travelling at a velocity sufiicient to retain substantially all the particles in suspension and at a temperature at which volatile oil constituents of the tar are vaporized from the tar particles while in suspension and retained in the vapor phase, and removing solid and liquid particles from the gases.

6. The method of distilling tar, which comprises spraying finely divided particles of tar to be distilled in a stream of hot coal-carbonization gases travelling at a velocity sufiicient to retain substantially all the particles in suspension and at a temperature at which volatile oil constituents of the tar are vaporized from the tar particles while in suspension and retained in the vapor phase, subjecting the gases and vapors to electrical precipitation to remove solid and liquid particles from the gases and cooling the gases to condense the vapors.

7. The method of operating coke-oven batteries, which comprises cooling the gases from the ovens of the battery to recover condensable constituents therefrom, suspending suchconstituents in finely divided form in the gases from selected ovens of the battery at a temperature at which oil con stituents are vaporized from said constituents and retained in the vapor phase, and removing solid and liquid particles from the resulting gases.

8. The method of operating coke-oven batteries, which comprises cooling the gases from the ovens of the battery to recover condensable constituents therefrom, suspending such constituents in finely divided form in the gases from selected ovens of the battery at a temperature at which oil constituents are vaporized from said constituents and retained in the vapor phase, subjecting the gases and vapors to electrical precipitation to remove solid and liquid particles from the resulting gases and cooling the gases to condense the vapors.

9. The method of distilling tar, which comprises spraying finely divided particles of the tar to be distilled into a stream of hot coal-carbonization gases and removing larger tar particles from the gases, smaller particles which will be carried in suspension by the gas being allowed to remain in contact with the gases to be distilled therein.

10. The method of distilling tar, which comprises spraying finely divided particles of the tar to be distilled into a stream of hot coal-carbonization gases and removing larger tar particles from the gases, smaller particles which will be carried in suspension by the gas being allowed to remain in contact with the gases until the desired distillation has been effected, thereafter removing suspended material from the gases which have been enriched in condensable constituents by the distillation, and cooling the resulting gases to condense vapors therefrom.

11. The method of operating a coal-carbonization plant, which comprises collecting the gases from selected coal-carbonization units of the plant, bringing tar into suspension therein while the gases are at suiiicient temperature to distill the tar so suspended and bringing the tar into such fine suspension therein that the tar will remain suspended therein throughout the distillation, and thereafter removing entrained par-ticles from the gases while the gases are still at high temperature.

12. In combination with a battery of coke ovens, a manifold for collecting the coal distillation gases from a plurality of the ovens, an atomizing chamber with means for maintaining a constant level of tar in the bottom thereof, a cylinder adapted to rotate on a horizontal axis therein and so situated as to dip slightly in the tar in the bottom of the atomizing chamber, a motor for rotating the cylinder at high speed, a contact chamber, an electrical precipitator, means for passing gases from the manifold to the atomizing chamber, from there to the contact chamber and from there to the electrical precipitator.

13. In combination with a battery of coke ovens, two separate gas collecting means connected with different ovens of the battery, a condenser connected with one of these gas collecting means, means for atomizing tar in the gases collected in the other gas collecting means, a contact chamber, an electrical precipitator, means for passing the gases from said other gas collecting means through the contact chamber and then through the precipitator and means for introducing tar from the condenser into the atomizing means.

14. In the distillation of tar the step which comprises introducing the tar into a stream of hot coal distillation gases in sufliciently finely divided condition to form a persistent suspension of the tar in the gas stream, the temperature of the gas stream being sufiiciently high so that oil constituents of the tar are vaporized and retained in the vapor phase.

15. In the distillation of tar the step which comprises introducing the tar into a stream of hot coal distillation gases in sufiiciently finely divided condition to form a persistent suspension of the tar in the gas stream, the temperature of the gas stream being sufiiciently high so that oil constituents of the tar are vaporized and retained in the vapor phase, and causing the tar to remain suspended in the gas stream during vaporization of its volatile constituents.

16. In combination with a battery of coke ovens, one gas collecting'means connected withovens of the battery, a second gas collecting means connected with other ovens of the battery, a condenser for the recovery of tar connected with the one gas collecting means, means for collecting tar recovered from the gases, means for suspending it in the gases collected in the second gas collecting means, a contact chamber, means for passing the gases from the second gas collecting means together with said tar suspended therein through the contact chamber.

17. In combination with a coke oven or retort, a gas chamber adapted to receive hot gases from said oven or retort, a spray chamber adjacent said gas chamber and adapted to contain a body of liquid, a passage from the spray chamber to the gas chamber, a spray roll of substantially circular cross section within said spray chamber and adapted to contact with the body of liquid and adapted to project the liquid into said gas chamber in such finely divided condition as to form a persistent suspension in the gases therein, and means for preventing the entrance of coarse particles of spray from the spray chamber to the gas chamber.

EDWARD H. ELLMS. 

